In a fuel cell which generates hydrogen rich gas supplied to the fuel cell by fuel reforming, in addition to hydrogen, carbon monoxide is generated in the reforming process, and carbon monoxide poisons the catalyst in the fuel cell. Therefore, a reforming system includes a shift reactor provided downstream of the reforming reactor to reduce the concentration of carbon monoxide.
Steam is required for the reforming reaction and shift reaction, and JP2000-306594A published by the Japanese Patent Office in 2000 discloses a method wherein the exhaust gas of the fuel cell is introduced into the reforming reactor to promote vaporization of the water supplied to the reforming reactor.